When performing oxy-fuel cutting on a 25 mm thick alloy steel, a welder finds that the cut starts cleanly but progressively loses penetration and eventually stops. The preheat flames appear strong and the oxygen cutting lever is fully depressed. What is the most probable cause?

Question: When performing oxy-fuel cutting on a 25 mm thick alloy steel, a welder finds that the cut starts cleanly but progressively loses penetration and eventually stops. The preheat flames appear strong and the oxygen cutting lever is fully depressed. What is the most probable cause?

Answer options: ✅ The cutting oxygen pressure is too low for the material thickness

• The preheat flame is too intense, causing premature oxidation
• The travel speed is too slow, allowing the cut to cool
• The cutting tip is obstructed or partially clogged

Correct answer: The cutting oxygen pressure is too low for the material thickness

Explanation: Losing penetration and the cut stopping, despite adequate preheat and full oxygen flow, often points to insufficient cutting oxygen pressure for the material thickness. Higher pressure is needed to sustain the exothermic reaction and expel molten metal through thicker sections.